3/8"-24 Zinc Plated Steel Fine Thread Castle Hex Nuts (16 pcs.)

Diameter: 3/8"
Thickness: 13/32"
Material: Steel
Finish: Zinc
Driver Type: 9/16" Wrench
Thread Size: 24 (Fine)
Type: Castle Nut
Unslotted Thickness and Height of Flat: 9/32"

Box of 16.

A castle nut, also known as a slotted nut, is a nut with slots (notches) cut into one end. The bolt or axle has one or two holes drilled through its threaded end. The nut is torqued properly and then, if the slot isn't aligned with the hole in the fastener, the nut is rotated to the nearest slot. The nut is then secured with a cotter pin or safety wire.